The present invention relates to aspects of an apparatus, method, and system for monitoring towed vehicles of a tractor-trailer vehicle. A tractor-trailer vehicle, which is equipped with a pneumatic brake system, includes a tractor and one or more towed vehicles depending upon the pay load and the regulations. Towed vehicles include trailers as well as dollies that are placed between trailers. A typical maximum number of towed vehicles in the towed vehicle train is five towed vehicles, for example, a “turnpike triple” which is made up of three trailers and two dollies.
In current tractor-trailer vehicle systems the tractor controls the diagnostics for the entire vehicle system. The tractor treats the towed portion of the vehicle train as a “dumb” vehicle, that is, the towed vehicle train is treated as an extension of the tractor. In reality, the length and weight of the vehicle train has substantial impact on the stability and control of the tractor-trailer vehicle, and the size and weight of the vehicle train can also vary from trip to trip, but nevertheless, the towed portion of the vehicle train is recognized as part of the same tractor. Currently there are no means by which a tractor can determine how many towed vehicles it has connected to it or the location or type of towed vehicle in the vehicle train at any given time.